Drills usable for a drilling process as a cutting tool have conventionally been known (for example, refer to Patent Document 1). The tool described in Patent Document 1 includes a base body (holder) having an axis, and two inserts (an inner cutting edge insert and an outer cutting edge insert) attached to the base body.
The inner cutting edge insert is different from the outer cutting edge insert in distance from the axis of the tool. Therefore, a shape of chips generated by the inner cutting edge insert is different from a shape of chips generated by the outer cutting edge insert. Specifically, the shape of the chips generated by the inner cutting edge insert extends spirally at a shorter pitch than the chips generated by the outer cutting edge insert, and the chips are likely to come together. The shape of the chips generated by the outer cutting edge insert has a longer pitch than the chips generated by the inner cutting edge insert, and the chips are less likely to come together. The shape of the chips generated by the inner cutting edge insert is different from the shape of the chips generated by the outer cutter edge insert, thus necessitating a chip discharge according to the shape. For example, when the chips generated by the outer cutting edge insert excessively extend without being divided in appropriate length, chip clogging may occur.